Glossary of Terms

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S

safety assessment

an analysis to evaluate the performance of an overall system and its impact, where the performance measure is radiological impact or some other global measure of impact on safety. See also performance assessment.

script

a set of computer commands that are performed upon user request or due to user interaction with a computer program

For example, when information is entered into an electronic form on a computer, a script may be used to process the information, such as adding numbers or to check spelling. The user can either request this action or it can happen automatically (for example, as soon as a user tabs between data entry fields).

sealed radioactive source

radioactive material that is permanently sealed in a capsule or closely bonded and in a solid form

segregating/sorting

the separation of materials (waste items) based on physical, chemical and radiological properties, typically to separate these materials for different processing options

server

see client-server

Short Lived

see waste classification

shredding

a waste treatment method to cut waste items into smaller pieces to facilitate handling or for subsequent treatment or conditioning (such as shredding followed by compaction)

site

the land area where any facility or activity is physically located or conducted, including adjacent land used in connection with the facility or activity

size reduction

a generic term for treatment methods used to reduce the size of waste items (see compaction and metal melting for examples)

sludge

a mixture of solid waste material and water

Sludges result from the concentration of contaminants in wastewater and water treatment processes. Typical wastewater sludges contain from 0.5 to 10 percent solid matter. Typical water treatment sludges contain 8 to 10 percent solids.

sludge washing

a treatment method used to extract soluble contaminants from sludge (includes "enhanced sludge washing")

Enhanced sludge washing (ESW) refers to the extraction of components from sludges using strong caustic solution, as opposed to simple sludge washing with only water. ESW removes nonradioactive components such as aluminum, chromium and phosphate salts from sludges.

solidification

the immobilization of gaseous, liquid or liquid-like materials by conversion into a solid waste form, usually with the intent of producing a physically stable material that is easier to handle and less dispersible. calcination, drying, cementation, bituminization and vitrification are some of the typical ways of solidifying liquid waste.

solvent extraction

a waste treatment method in which a generally aqueous solution is mixed with an immiscible solvent to transfer one or more components into the solvent (typically used to separate chemicals or radionuclides)

The solute dissolves more readily and becomes more concentrated in the solvent in which it has a higher solubility. A partial separation occurs when a number of solutes have different relative solubilities in the two solvents used.

special fissionable material

a term used in the Statute of the IAEA with essentially the following meaning, but explicitly excluding source material:

Plutonium except that with isotopic concentration exceeding 80% in plutonium-238; uranium-233; uranium enriched in the isotope 235 or 233; uranium containing the mixture of isotopes as occurring in nature other than in the form of ore or ore-residue; any material containing one or more of the foregoing

Source material is defined as uranium containing the mixture of isotopes occurring in nature; uranium depleted in the isotope 235; thorium; any of the foregoing in the form of metal, alloy, chemical compound, or concentrate; any other material containing one or more of the foregoing in such concentration as the Board of Governors shall from time to time determine; and such other material as the Board of Governors shall from time to time determine

spent

a term typically used for radioactive materials in the following context:

spent fuel: nuclear fuel removed from a reactor following irradiation, which is no longer usable in its present form because of depletion of fissile material, poison build-up or radiation damage.

spent sealed radioactive source (SRS): an SRS that is no longer suitable for its intended purpose as a result of radioactive decay

Note: in the initial data collection cycles, Member States are not being asked to report spent fuel inventories. However, if a Member State uses a waste class matrix to equate spent fuel with High Level Waste, it may report spent fuel as HLW

SRS

see sealed radioactive source

stabilization

conversion of chemically active or readily dispersible matter into an inert or less harmful form

storage

the holding of spent fuel or radioactive waste in a facility that provides for its containment, with the intention of retrieval.

Storage is by definition an interim measure, and the term interim storage would therefore be appropriate only to refer to short term temporary storage when contrasting this with the longer term fate of the waste. Storage as defined above should not be described as interim storage.

In the NEWMDB, interim storage applies to waste that is being held for a short time while awaiting transfer to an available disposition option. For example, waste being stored in a processing facility awaiting transfer to an available storage or disposal facility would be considered to be in interim storage. If waste is being storage because there is no place to send it, for example, it is being stored because there is no processing or disposal alternative available, the waste would be considered to be in storage, not in interim storage. In general, the NEWMDB considers temporary to imply periods of less than one year.

storage facility

a nuclear facility where waste is emplaced for storage

storage unit

A single storage facility may use various types of storage, such as tanks for liquids, bunkers for low activity waste, and silos for higher activity waste. The NEWMDB uses the concept of storage units to identify the various types of storage used.

stored

see storage

super compaction

used in radioactive waste management facilities to indicate high force compaction, typically ranging from 750 -2000 ton compactors

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